Radiation Therapy Requirements for DCIS Lumpectomy
Standard Radiation Protocol
- The American Cancer Society recommends radiation therapy typically begins 2-4 weeks after uncomplicated breast-conserving surgery, once adequate healing has occurred 3
- Treatment is delivered using opposed tangential fields to encompass the tumor bed, surrounding tissue, and most of the ipsilateral breast 2
- Each treatment field should be administered daily (Monday through Friday) for a total of 25 fractions 1, 4
Dosage Details
- Standard whole-breast radiation therapy dose is 4,500 to 5,000 cGy delivered at 180 to 200 cGy per fraction 6
- Higher energy photons (≥10 MV) may be indicated for very large-breasted women or patients with significant dose inhomogeneity 7
Boost Considerations
- Controversy exists regarding the need for an additional boost dose to the primary site 4
- When used, boost irradiation is typically delivered using electron beam or interstitial implantation 2
- A boost increases the total dose to the primary tumor site to approximately 6,000 to 6,600 cGy 4
Important Considerations and Precautions
- Nodal irradiation is unnecessary for patients with DCIS 8
- To minimize radiation pneumonitis risk, no more than 3-3.5 cm of lung should be treated 5
- For left-sided lesions, efforts should be made to minimize heart exposure in tangential fields 2
- Patient positioning and treatment planning should ensure reproducibility and dose homogeneity 3